This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Human malaria parasites that sicken more than five percent of the global human population annually comprise only four species in a single genus. This represents a miniscule fraction of the phylogenetic diversity of malaria, most of which occurs in birds and is undescribed. An adequate description of avian malaria diversity and host-parasite dynamics is needed to understand the evolution of the human parasites. In fieldwork since 2007, we have initiated the first large-scale survey of avian malaria in the tropical Andes, the premier global hotspot for alpha- and beta-diversity of birds. We have collected over 6000 frozen tissues and 3000 blood samples across a 4000m elevational gradient in Peru, representing 500 host species from 46 families, while rigorously documenting host and parasite materials and data in a museum database. A preliminary screening by microscopy of at least 100 samples from each of five elevations shows two novel findings: (1) a dramatic mid-elevation peak in malaria infection rate corresponding with the subtropical 'cloud forest'zone;and (2) striking variation in malaria prevalence among avian clades, with clades that expanded to South America after the formation of the Isthmus of Panama having the highest rates of infection. The aims of this project are (1) to describe malaria parasite diversity across a steep temperature and pressure gradient along which there is high diversity and turnover of host species;and (2) to determine the effects of host phylogeny, biogeography, and respiratory adaptations to altitude on susceptibility to avian malaria.